Looks to be a selenium cell meter. Originally self powered; no battery needed.

Most of the time the cell has lost its sensitivity due to old age , or its delicate contact areas have corroded.

If working, the meter needle moved in response to the amount of light the cell 'saw' You followed the black or silver band from the meter needle position to a numbered scale, with the scale first set to correspond to the speed of film in use. The film speed might be calibrated in asa, or din values or both.

The meter reading then usually gave you the fastest shutter speed and effective aperture to use for that sensitivity of flim.

You, the user, set the exposure dial and aperture lever or dial to suit that reading, or set it to an equivalent slower shutter and smaller aperture that gives and equivalent exposure.

Hope this helps your comprehension. I have seen a half dozen of these meant for Polariods, etc. None I have seen have ever worked past 1990.

Mine still works as it has been kept on the dark and still reads through the entire scale without a problem. My issue is reading the fstop and shutter speed of the dial. I can rotate the outter ring but that is it. On my other older meters I can set the film speed on a third inner dail and then the outer is straigth forward. This one on the other

Looks to be a selenium cell meter. Originally self powered; no battery needed.

Most of the time the cell has lost its sensitivity due to old age , or its delicate contact areas have corroded.

If working, the meter needle moved in response to the amount of light the cell 'saw' You followed the black or silver band from the meter needle position to a numbered scale, with the scale first set to correspond to the speed of film in use. The film speed might be calibrated in asa, or din values or both.

The meter reading then usually gave you the fastest shutter speed and effective aperture to use for that sensitivity of flim.

You, the user, set the exposure dial and aperture lever or dial to suit that reading, or set it to an equivalent slower shutter and smaller aperture that gives and equivalent exposure.

Hope this helps your comprehension. I have seen a half dozen of these meant for Polariods, etc. None I have seen have ever worked past 1990.

"The meter reading then usually gave you the fastest shutter speed and effective aperture to use for that sensitivity of flim." thanks a lot! Still I dont know how to interpret this values on the dial.

Turn the dial until the shutter speed you are using is adjacent to the film speed (EI) you are using.

As the needle moves in response to light, it will point to a number adjacent to an f/stop.

The f/stop is the one you need to set on your camera (assuming the meter is accurate).

If the dial rotates appropriately, you may be able to start off instead by setting the f/stop you intend to use adjacent to the film EI, and read the shutter speed closest to the needle.

Actually quite an elegant approach.

Matt

“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

Turn the dial until the shutter speed you are using is adjacent to the film speed (EI) you are using.

As the needle moves in response to light, it will point to a number adjacent to an f/stop.

The f/stop is the one you need to set on your camera (assuming the meter is accurate).

If the dial rotates appropriately, you may be able to start off instead by setting the f/stop you intend to use adjacent to the film EI, and read the shutter speed closest to the needle.

Actually quite an elegant approach.

Ty for the input! I just tested that reading technique and it seems consistent, sadly only for reading above a certain threshold, only well lid situations.
I cannot, if you see the image, set speeds at low lights like 2.8 @ 1/60. For example, for using an fstop of f/1.4
I would need to use a speed of 1/1000 @ ASA 400, because the needle will be on the very left border and setting the f1.4 on it would cause tthe 1/1000 to fall on the ASA 400, which is clearly a false reading, since a needle all the way to the left is very low light and a lower ~1/30 sec is needed at ~1.8 but not close to the needed value for f/1.4.

“Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

Set the ASA (image shows you are shooting 125 ASA Plus-X)
Point to light and read look at the needle.
Read the number (EV) the needle is pointing to (13 in the image)
Set EV 13 on your Rollei's Compur Synchro shutter.